In the days of yore, the file locking code was primarily protected by the BKL. That changed in commit 72f98e72551fa (locks: turn lock_flocks into a spinlock), at which point the code was changed to be protected by a conventional spinlock (mostly due to a push to finally eliminate the BKL). Since then, the code has been changed to use the i_lock instead of a global spinlock, but it's still under a spinlock. With that change, several functions now no longer can block when they originally could. This is a particular problem with the fl_release_private operation. In NFSv4, that operation is used to kick off a RELEASE_LOCKOWNER or FREE_STATEID call, and that requires being able to do an allocation. This was reported by Josh Stone here: https://bugzilla.redhat.com/show_bug.cgi?id=1089092 My initial stab at fixing this involved moving this to a workqueue, but Trond pointed out the above change was technically a regression with the way the spinlocking in the file locking code works, and suggested an alternate approach to fixing it. This set focuses on moving most of the locks_release_private calls outside of the inode->i_lock. There are still a few that are done under the i_lock in the lease handling code. Cleaning up the use of the i_lock in the lease code is a larger project which we'll have to tackle at some point, but there are some other cleanups that will need to happen first. Absent any objections, I'll plan to merge these for 3.18. Jeff Layton (5): locks: don't call locks_release_private from locks_copy_lock locks: don't reuse file_lock in __posix_lock_file locks: defer freeing locks in locks_delete_lock until after i_lock has been dropped locks: move locks_free_lock calls in do_fcntl_add_lease outside spinlock locks: update Locking documentation to clarify fl_release_private behavior Documentation/filesystems/Locking | 6 ++- fs/locks.c | 80 +++++++++++++++++++++++++-------------- 2 files changed, 57 insertions(+), 29 deletions(-) -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html